At present, the main technology for cutting a display substrate is such a technology that uses a cutter wheel as a tool to cut a glass substrate. In this technology, the surface of the glass substrate is cut by the cutter wheel to form cracks and then an external force is applied to the glass substrate so that the glass substrate is broken along the cracks.
However, this technology is not suitable for substrates made of a flexible material (plastic), for which a laser cutting method is generally used instead.
Generally, only substrates made of a flexible material and having high laser absorptivity can be cut by a laser.
As shown in FIG. 1, when the substrate 1 to be cut is subjected to laser cutting, a laser performs cutting along a cutting line 2. As the material of the substrate 1 has high laser absorptivity, a region on both sides of the cutting line 2 is apt to absorb heat and thus be carbonized to form a carbonization region 3 (regions between both sides of the cutting line 2 and dotted lines in FIG. 1). The carbonization region 3 is a black region, which affects the appearance of the display substrate. Meanwhile, as the carbonization region 3 is too wide relative to the cutting line 2 (generally has a width several times as large as that of the cutting line 2), the area (material) of the substrate 1 is wasted. Additionally, the dust generated when breaking the carbonization region 3 will influence the subsequent process treatment on the substrate 1.
As is well known, the area of the substrate 1 may be utilized more effectively by reducing the width of the cutting line 2, and the waste of material may be thus avoided.
There is a method in the prior art for reducing the width of the cutting line 2 by narrowing the focus point of laser beam. However, narrowing the focus point of laser beam increases the laser energy per unit area, and as a result, the carbonized level of the carbonization region 3 is more significant, and even reaches the extent of coking.
Hence, there is an urgent need to develop a method capable of reducing the width of the cutting line 2 while avoiding the generation of the carbonization region 3.